System and method for managing automation systems with jerk compensation

ABSTRACT

A method for managing an automation system involving asynchronous and synchronous zones, the method including: determining when a moving element enters a merge zone between an asynchronous zone and a synchronous zone; calculating additive jerk to be applied to the moving element, In some cases, the additive jerk is based on predetermined compensation profiles; determining if the master position change is different than a base logged; if so, interpolating additive jerk based on movement characteristics of the moving element; in either event, applying the additive jerk to the moving element; and determining if the merge is completed and, if yes, ending the merge and continue with synchronous operation but, if no, returning to calculating the additive jerk and repeat. A system including a processor/controller and a memory including instructions, which when executed by the processor/controller, perform the method.

RELATED APPLICATION

The present disclosure claims priority to U.S. Provisional Pat. App. No.63/281,977, filed Nov. 22, 2021, which is hereby incorporated herein byreference.

FIELD

The present disclosure relates generally to a system and method formanaging automation systems and equipment. More particularly, thepresent, disclosure relates to a system and method for managingautomation systems using jerk compensation.

BACKGROUND

Modern manufacturing and automation systems and processes are becomingmore complex, at least in part because these systems and processes arerequired to be fast, accurate and repeatable over longer periods oftime. These systems and processes are expected to provide appropriateproduct quality in short time frames. These systems and processes alsoseek to provide high machine efficiency with low downtime formaintenance, trouble-shooting and the like.

Since manufacturing and automation systems have complex requirementsthere can be situations where products from differing manufacturers needto be implemented into a single automation system. Further, in order toget higher levels of efficiency, it can be necessary to co-ordinate theactivities (e.g. motion profiles) of various different types ofautomation systems from various manufacturers. However, generallyspeaking, automation systems manufacturers may try to limit the abilityto interchange hardware so that a buyer will only use a particularmanufacturers hardware. One way in which the ability to interchangehardware is the use of different communication protocols. While thereare some known solutions that attempt to convert between differentcommunication protocols by using industrial computers or the like, inpractice this process can be very complex and needs to be updatedregularly. In a situation where there needs to be co-ordination betweenor among hardware, the complexity is even higher due to the need forreal-time or near real-time communication and the latency that can existin the process of conversion or in the communication protocol itself.

As such, there is a need for improved system and method for managingautomation systems and equipment in manufacturing environments.

SUMMARY

According to an aspect herein, there is provided a method for managingan automation system involving asynchronous and synchronous zones, themethod including: determining when a moving element enters a merge zonebetween an asynchronous zone and a synchronous zone; calculatingadditive jerk to be applied to the moving element, wherein the additivejerk is based on compensation profiles; determine if the master positionchange is different than a base logged; if so, interpolate a setpointposition from a jerk profile based on movement characteristics of themoving element; in either event, apply the jerk profile to the movingelement; and determine if the merge is completed, if yes, end the mergeand continue with synchronous operation but, if no, return to calculatethe additive jerk and repeat.

In some cases, the compensation profiles may be determined in advance toreduce computation time and complexity.

In some cases, the method may further include: determining worse casetime remaining before entering the synchronous zone; determine if themoving element the moving element needs to stop; if so, stop at minimumstopping position and determine when to start moving and next possibleindex; in either case, determine acceleration compensation, velocitycompensation and position compensation profile to match velocity andposition; and determine the movement characteristics based on thecompensation profiles.

According to another aspect herein, there is provided a method formanaging an automation system involving asynchronous and synchronouszones, the method including: determining when a moving element enters amerge zone between an asynchronous zone and a synchronous zone;calculating additive jerk to be applied to the moving element, In somecases, the additive jerk is based on predetermined compensationprofiles; determining if the master position change is different than abase logged; if so, interpolating additive jerk based on movementcharacteristics of the moving element; in either event, applying theadditive jerk to the moving element; and determining if the merge iscompleted and, if yes, ending the merge and continue with synchronousoperation but, if no, returning to calculating the additive jerk andrepeat.

In some cases, the predetermined compensation profiles may be determinedin advance to reduce computation time and complexity.

In some cases, the predetermined compensation profiles may include avelocity compensation profile and a position compensation profile.

In some cases, the calculating additive jerk based on predeterminedcompensation profiles may include determining the movementcharacteristics of the moving element based on the compensationprofiles.

In some cases, the method may further include determining if the movingelement needs to stop prior to or within the merge zone to allowsynchronization.

In some cases, the method may further include calculating a minimum stopposition based on maximum entry velocity.

In some cases, the method may further include: determining worst casetime remaining before entering the synchronous zone; determining if themoving element needs to stop; if so, stop the moving element at aminimum stopping position and determine when to start moving and nextpossible index; in either case, determining velocity compensation andposition compensation profiles to match velocity and position; anddetermining the movement characteristics based on the compensationprofiles.

According to another aspect herein, there is provided a system formanaging an automation system involving asynchronous and synchronouszones, the system including: a first controller for controlling a firstsynchronous element; a second controller for controlling at least asecond synchronous element; a configuration module for configuring theautomation system; a memory storing instructions that, when executed bythe second controller, cause the second controller to: determine when amoving element enters a merge zone between an asynchronous zone and asynchronous zone; calculate additive jerk to be applied to the movingelement, In some cases, the additive jerk is based on predeterminedcompensation profiles; determine if the master position change isdifferent than a base logged; if so, interpolate additive jerk based onmovement characteristics of the moving element; in either event, applythe additive jerk to the moving element; and determine if the merge iscompleted and, if yes, end the merge and continue with synchronousoperation but, if no, return to calculating the additive jerk andrepeat.

In some cases, the predetermined compensation profiles may be determinedin advance to reduce computation time and complexity.

In some cases, the predetermined compensation profiles may include avelocity compensation profile and a position compensation profile.

In some cases, the calculating additive jerk based on predeterminedcompensation profiles may include determining the movementcharacteristics of the moving element based on the compensationprofiles.

In some cases, the instructions may further include determining if themoving element needs to stop prior to or within the merge zone to allowsynchronization.

In some cases, the instructions may further include causing the secondcontroller to calculate a minimum stop position based on maximum entryvelocity.

In some cases, the instructions may further include causing the secondcontroller to: determine a worst case time remaining before entering thesynchronous zone; determine if the moving element needs to stop; if so,stop the moving element at a minimum stopping position and determinewhen to start moving and next possible index; in either case, determinevelocity compensation and position compensation profile to matchvelocity and position; and determine the movement characteristics basedon the compensation profiles.

Other aspects and features of the embodiments of the system and methodwill become apparent to those ordinarily skilled in the art upon reviewof the following description of specific embodiments in conjunction withthe accompanying figures.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the system and method will now be described, by way ofexample only, with reference to the attached Figures, wherein:

FIG. 1 is a diagram illustrating an example of an automation systemincluding a conveyor system and various automation stations;

FIG. 2 is a block diagram illustrating an embodiment of a system formanaging automation systems according to an embodiment;

FIG. 3A is a flow chart for a method for managing automation systemsaccording to an embodiment;

FIG. 3B is a flowchart of an embodiment for processing an incomingmaster signal, irrespective of the source;

FIG. 3C illustrates a corrected input master signal portion generated byreverse engineering the input master signal's trajectory planner;

FIG. 4 is a flow chart for another method for managing automationsystems according to an embodiment;

FIG. 5 illustrates a base motion profile diagram for parameters relatingto a merge from an asynchronous zone to a synchronous zone;

FIG. 6 illustrates an ideal alignment of a pallet to an entry profilevelocity merge using an embodiment of the system and method herein; and

FIG. 7 illustrates a practical alignment of a pallet to an entry profilevelocity merge, respecting a changing master's profile using anembodiment of the system and method herein;

FIG. 8 illustrates an example predefined motion profile that movingelements would follow on a conveyor in relation to a master controller;

FIGS. 9 /10 are tables showing example master control information/dataflowing from a PLC over a communication network;

FIG. 11A illustrates an example of the use of an offset of a PLC'scommand of its servos by a latency delay determined for informationtransfer to a synchronous element such as a moving element on aconveyor;

FIG. 11B illustrates one example of timing of a PLC task and a conveyor(SuperTrak) task based on signal time;

FIG. 12 shows velocity and position setpoints and inputs during thestart of a deceleration;

FIG. 13A shows a compensation curve being employed when slight drift isnoted in the velocity setpoint vs. input;

FIG. 13B shows the same curve as FIG. 13A but with labelling to show thedrift and compensation areas of the graph;

FIG. 14 shows the additive jerk profiles separately (calculated for theacceleration, velocity and position compensation curves); and

FIG. 15 illustrates the use of a master signal and compensation betweentwo conveyors providing a synchronous area.

DETAILED DESCRIPTION

The following description, with reference to the accompanying drawings,is provided to assist in understanding the example embodiments. Thefollowing description includes various specific details to assist inthat understanding but these are to be regarded as merely examples.Accordingly, those of ordinary skill in the art will recognize that thevarious embodiments described herein and changes and modificationsthereto, including the use of elements of one embodiment with elementsof another embodiment, can be made without departing from the scope andspirit of the appended claims and their equivalents. In addition,descriptions of well-known functions and constructions may be omittedfor clarity and conciseness.

The terms and words used in the following description and claims are notlimited to their bibliographical meanings but are meant to beinterpreted in context and used to enable a clear and consistentunderstanding.

Generally, the present document provides for a system and method formanaging automation systems. Embodiments of the system and method hereinare intended to allow for integration of various manufacturer's productsand synchronization of various manufacturer's products by compensatingfor network delay and variability between the manufacturer's productsalong with the designation/setup of the master controller (for example,a programmable logic controller (PLC)), which can provide the mastersignal to which other controllers can be synchronized. Embodiments ofthe system and method herein enable the use of different vendors' PLCs,drives and servos (for example, Siemens™, Omron™ and Rockwell™) as asource or master signal to drive operation of a conveyor in asynchronized way, without any significant performance loss for mostmachine applications.

While the concepts herein can be applied in various environments, thefollowing description will focus on the use of automationstations/equipment together with a linear motor conveyor. Conveyors inan automation environment will typically have a plurality of automationstations placed along the conveyor and will have a variety ofparameters/settings and the like that generally need to be configuredproperly in order for the conveyor and related automation stations toproperly function together.

Automation stations are used on manufacturing or production lines tohandle manufacturing operations and are typically arranged adjacent to aconveyor system for feeding parts or the like. An automation station mayinclude a single piece of equipment/machine in a production line, suchas a press, pick & place device or the like, but may also include acomplex system involving robots, manipulators, and the like. Further,the automation station may be positioned to receive, via a conveyor, amoving element of the conveyor system, which may include at least onecarrier/pallet per moving element configured to move a part into and/orout of an automation station. Generally speaking, automationstations/equipment have been difficult to manage, particularly inrelation to interactions with conveyors, due to the complexity ofinteractions that can be required, differing communications protocols,and the like.

Conventional systems for the management of automation systems andassembly lines generally have difficulty integrating automationequipment from differing vendors with each other or with conveyorsystems, including linear motor conveyor systems. Many parameters arerequired to be considered during automation operations together with aconveyor system, including, for example, parameters such as spacing,timing, trajectory, temperature, collision avoidance and the like.

FIG. 1 shows an example configuration of an automation system 100,including a conveyor system 102 and at least one automation station 110.In this case, the conveyor system 102 is a linear motor conveyor systemincluding a track providing a linear motor that drives moving elementsalong the track using magnetic fields. At least one automation station,or automation element, 105 (which in the current example includes 23automation stations 105) may be or include, for example, machines,sensors, servos, devices, or equipment, or a combination of machines,devices, or equipment, or the like. Each automation station 105 mayrequire a certain amount of processing time and may further includevarious parameters related to their operation. As can be seen from FIG.1 , various types of automation stations may be needed and theseautomation stations may come from a variety of manufacturers.

The conveyor 102 includes moving elements 110 that are configured totravel on the conveyor 102, stopping at one or more target set, points(“targets”) that relate to various automation stations 105 in order tohave the automation station function applied to an item or object (“partor product”) being carried by the moving element 110. In some cases,there may further be loading or unloading stations where the products oritems are placed on or removed from the moving elements. Some of theautomation stations 105 will operate in an asynchronous mode or be in anasynchronous area, in which, a moving element 110 will stop at anautomation station 105 and the station will operate on a part on themoving element or the like. Generally, in an asynchronous mode, theconveyor system and automation stations 105 can accommodate variablecycle times and loading. However, in some areas, the conveyor system 102and automation stations 105 may operate in a synchronization mode orsynchronization area (indicated as synchronization area 120), in orderto achieve higher speed throughput for automation stations that may becontrolled by software or mechanical methods to work synchronously. Forexample, the automation station may be cammed either mechanically or viasoftware—to repeat an action in a predefined manner continuously. Thesesynchronous automation stations would generally have fixed cycle times,which allows for synchronization, for example, by following a mastersignal (which may be a software signal or the like as described infurther detail in the description of FIG. 2 ). Similarly, movingelements 110 could be configured to follow a predefined motion profile(for example, such as that illustrated in FIG. 8 ), within thesynchronous area 120, based on the master signal. In automation systems100 where not all automation stations 105 are synchronized in some way,transitioning between an asynchronous area and a synchronous area 120can sometimes require a merging zone 125. The merging zone 125 can beused to adjust/align/synchronize a moving element 110 to the softwaremaster signal so that the moving element can begin a motion profilesequence (example shown in FIG. 8 ) at the appropriate timing forentering the synchronous area 120. FIG. 4 and related descriptionoutlines an embodiment of a process for handling/managing of thismerging zone. In order for the conveyor system 100 to work well with thevarious automation stations, various configuration parameters must bemanaged such that the moving elements will work in synchronization withthe operations of the one or more automation stations. Thissynchronization must generally be accomplished at high speed and over alarge number of cycles in order to provide a high throughput whilereducing any bottlenecks. Further, the moving elements 110 are intendedto move from position to position without colliding and ensuring, properorientation for processing at each automation station.

FIG. 2 illustrates a system 200 for managing automation systemsaccording to an embodiment. As noted above, the automation system 100that is managed by the system 200 may include a conveyor 102 and aplurality of automation stations 105 and, further, the automationstations 105 may be in asynchronous areas/zones (automation stations105A) or synchronous areas/zones (automation stations 105B). The system200 includes one or more programmable logic controllers (PLC) 205 (whichare typically associated with an automation station and control theelements of the automation station), a configuration module 210, adisplay/interface 215, and at least one processor 220. The configurationmodule 210 may include a connection to an internal or external datasource, such as a database 225 or the like.

The PLC 210 and the processor 220 can be configured to allow input ofand/or receive data related to various parameters related to theautomation system. For example, there may be a display/interface (humanmachine interface (HMI)) 215 for a user 240 to input data related to theautomation system, including the conveyor and the automation stations.In some cases, there may be access to one or more outside data sources225, via, for example the configuration module 210, for data from thirdparty data sources, for automation station/equipment parameters and thelike. The configuration module 210 may obtain various parameters fromthe database 225 such as, for example, previously saved data relating toknown or previously input automation system elements or the like. Theinput or received data may be stored in the database 225 or the like. Aswill be understood, the database 225 may be distributed across one orseveral memories and may be accessed via a network or the like.

The configuration module 210 is configured to review the input data todetermine the parameters related to configuration of the automationsystem. The configuration module 210 takes input data, for example,relating to manufacturer, product name/number, functionality, or thelike and prepares a configuration of the automation system that willaccount for communication protocol conversion, latency times, and thelike. The configuration module 210 may also allow for further input andadjustments to be made by, for example, a user or users 240. Generally,the configuration module 210 is configured to review the input data andconfiguration parameters and make adjustments so that the automationstations and conveyor can be in communication and synchronouslycontrolled (i.e. move in a synchronous manner under the control of amaster signal) in synchronous zones/areas.

The display/interface 215 provides output information to the end user240. The processor 220 processes data from the PLC 205 and providesprocessing power to the configuration module 210 for performingembodiments of the method of managing automation systems describedherein. The processor 220 also provides output to the display.

Each of the PLC 205 and the processor 220 may include a master controlto provide the master control signal used in synchronous areas. Themaster control may be in hardware or software (virtual). In thisexample, the processor 220 includes a virtual software processor master250. The PLC 205 may also have a PLC virtual master 255, which can beused in the event of external master control (where the master controlwill ‘propagate’ a master control signal/information to the processor(more information on this process is describe below with regard to FIGS.3A, 3B, and 3C), including the state machine/elements involved). In somecases, the PLC will set and control the virtual master in the processor.The PLC will also generally control asynchronous areas and theasynchronous automation stations 105A. In the event of external mastercontrol (as described with FIGS. 3A, 3B and 3C) the PLC can controlsynchronized areas and synchronized automation stations 105B, otherwisethe processor can control the synchronized areas and synchronizedautomation stations 105B. The configuration module 220 may be furtherenhanced via machine learning, artificial intelligence or the like basedon results from previous configurations.

FIG. 3A illustrates a method 300 for managing automation systemsaccording to an embodiment. As an example, the method 300 can relate toimplementing an external master control signal (for example from aparticular manufacturer's PLC or the like) for use when a device with aPLC is synchronized with a conveyor system or the like. In thisembodiment, the PLC may control elements that are directly connected tothe PLC in some manner, referred to as a “connected element” or “machineelement” and may also control an element that may not be directlyconnected but that is intended to operate synchronously with theconnected elements, referred to as a “synchronous element”. Connectedelements may include servos, switches, mechanical elements and the like.Synchronous elements may include conveyor moving elements (as in thisembodiment), other devices having their own PLC or the like.

Generally, the method 300 includes: send master control information(master signal) from, for example, a PLC to connected elements or over acommunication network (an example of typical data/information is shownin FIGS. 9 /10) at 305. If necessary at 310, offset the PLC's command ofone or both of the connected element, such as servos and the like, andexternal synchronous elements, such as a conveyor (e.g. SuperTrak™conveyor) or the like, based on a compensation profile for eachconnected or synchronouse element. As one example, the compensationprofile may be related to a latency delay determined based on a timeperiod for information transfer to the connected element and/or thesynchronous element that follows the master signal. In this example, thelatency delay may vary depending on communication protocol, thecharacteristics of connected or synchronous element (type of ormanufacturer of the equipment), the data being sent, or the like and canbe determined by the configuration module in advance. Some examplecommunication protocols include Profinet™ IRT, EtherCAT™, EthernetIP™,and the like). FIG. 11A is an illustration of this approach to handlelatency compensation.

After compensation, the compensated master signal is received andprocessed at each of the connected elements (at 315) and the synchronouselements (at 320) in a synchronous manner. It is noted that the mastersignal may be a raw signal or may be generated based on a raw signal. Itwill be understood that directly connected elements may require littleor no compensation whereas external synchronous elements may requiremore detailed compensation. In FIG. 3A, the processing of the raw orgenerated incoming master signal by the synchronous element can employcompensation algorithms and look-ahead/prediction algorithms at 325 toalign real-time with the master signal while filtering out instabilitiesin the input signal such as those described below and with regard toFIG. 3B. It will be understood that the selection of the master signalfrom among the devices, conveyors, or the like can be made based onaspects such as, which element controls the most time-sensitivesynchronous elements, which device has the ability to support thecompensation algorithms, or the like.

FIG. 3B illustrates a flowchart of an embodiment for processing anincoming master signal, irrespective of the source. In some cases, theapproach in FIG. 3B is made possible by generating a corrected raw inputsignal (generated input signal) based on the data received when thesource is unable to send data in the format requested. For example, FIG.3C illustrates a corrected input master signal portion generated byreverse engineering the input master signal's trajectory planner. Theblue line (330) shows the input sent from the PLC and the orange line(335) shows the corrected input. Further, in some cases, if thetrajectory generation method from the master signal is not exactlyknown, a generic compensation profile can be used that spans anyindividual uncertain portions of a master signal's trajectory. This typeof generated profile is illustrated for the secondary portion of anacceleration curve in FIG. 3C via the orange line (335). The generationof the master signal can also correct for any error or delay in theinput master signal, similar to the corrected input portion. Similarcompensation algorithms as in FIG. 3B can then be used to re-align withthe generated or corrected input signals, allowing for a genericizedcompensation implementation. While following a generated master signal,small positional and velocity errors may be induced which can becorrected via a compensation curve once the master signal trajectory hasreached a constant velocity.

In most cases, it is beneficial if the master signal can utilize apredetermined period (such as, for example, 4 ms as illustrated in FIG.11B) for unique information/data while sending the actual data atanother predetermined period (e.g. 1 ms) intervals, that is the samemaster signal is sent every 1 ms but then updated every 4 ms. Thesynchronized item (such as a conveyor) can then be configured to processtasks at another time interval (e.g. 800 us). In this way, 4 data pointsthat are the same can be received within the same time as 5 data pointsfrom the synchronized element (800 us interval). Generally speaking, theperiod on the receiving end (synchronized element) can be a divisor ofthe master signal's period.

In some cases, the latency delay used in the method can be determinedexperimentally by sending and echoing timestamps back and forth from onedevice to another. By dividing the time stamp difference by 2, theapproximate one-way propagation delay can be determined. Typically, thedelay can differ on a machine-by-machine basis, depending on thecommunication protocol method used, length of cable between PLC andmachine, and other variables. In some cases, a mathematical relationshipamong the variables can be determined and kept in a table or the likefor lookup, for example, when an alternate supplier device, longercable, or the like is used as a replacement or the like. Oncedetermined, the latency delay can be used to offset the PLC's commandsto connected elements (e.g. servos or the like) that the PLC operates inorder to have the connected elements receive inputs from the PLC atapproximately the same rate as a synchronized element (e.g. a conveyoror the like) receives a master signal sent from the PLC. In one example,this delay was found to be stable (˜0.05 ms of variation) in testapplications when using off-the shelf hardware. Using this information,compensation algorithms can be determined for use upon a change inacceleration of the master signal, or if signals began to drift apartdue to delays or instability in the network. In one example, where themaster signal sends the commanded velocity and acceleration, it ispossible to filter or process information that is received at a delaywithout having to make erroneous adjustments to a calculated mastersignal position. In this case, if, while traveling at constant velocity,a connected or synchronous element receives a unique master position,but the master position is received one scan late, it is possible toverify that the commanded velocity and acceleration of the systemhaven't changed, meaning the master signal should have stayed on thepath that the master signal was on previously, and then filter thesetpoint information based on a predicted/logical next setpoint,checking the setpoint information with any previous setpoints that mayhave been assigned to the master to see if instability in the signal hasoccurred. If there is an instability, the instabilities can be filteredout by adapting a methodology of always being slightly behind, ormatching in-line, with the master signal. By staying behind the mastersignal by a value less than the least significant digit of the normallyprocessed signal, it is possible to effectively ignore instabilitiessuch as late erroneous information since the late information wouldalways result in being ahead of the master signal. If this kind ofinstability occurs, the instability is typically accompanied, at somepoint, by a correction signal that, may be received one scan early, dueto the master signal following a periodic send clock, which will cancelthe previous delay. In this case, where the commanded velocity andacceleration are also sent, this allows logical predictions to be madeand the system can ignore/filter small instabilities in the signal. Oneof skill will understand that it is also possible to employ the reverseapproach of configuring the system to be slightly ahead of the mastersignal and being able to filter when we receive data early for a scan,which should eventually be accompanied by data that is a scan late. Whenthe commanded velocity or acceleration change; the system can employ acompensation curve. The curve can span a configured number of processscans to correct any ‘missed’ positional, velocity and acceleration (ifusing jerk) changes in the X ms the scan was delayed by (in some cases,this is generally 4 ms (PLC servo task cycle time)). A compensationcurve can also be employed if there is any drift noted while running(and not covered by an existing compensation). Generally, the system canbe configured such that a compensation may only over-write anothercompensation in the event of a change in commanded velocity oracceleration, or in the event of a change in the jerk-input parameter.FIG. 12 shows velocity and position setpoints and inputs during thestart, of a deceleration. FIG. 13A shows a compensation curve beingemployed when slight drift is noted in the velocity setpoint vs. input.FIG. 13B shows the same curve as FIG. 13A but with labelling to show thedrift and compensation areas of the graph. The compensation can becarried through in such a way as to also correct for any positionalerror, or lack thereof. A system or method using this type of externalmaster implementation may also use jerk as a parameter if the supplyingPLC is able to provide it. If jerk is used then a commanded accelerationshould also be supplied (since it would be understood that theacceleration is no longer instantaneous).

FIG. 3B illustrates an embodiment of a compensation method 350 of thetype that may be used when the master signal is received at thesynchronized element. At 355, the system receives or determines inputdata. At 360, the system determines if the input signal makes use ofjerk as a parameter and, if so, if the parameter needs processing. Theterm jerk refers to the rate at which acceleration is increasing ordecreasing and can be important in controlling moving elements,particularly on conveyors. Using jerk as a parameter enables a system tohave smooth acceleration and deceleration profiles, and thus improve theaccuracy of an external master control implementation. If yes at 360,then at 365, the system filters/processes the jerk and the commandedacceleration input for the virtual master of the processor for, forexample, the conveyor.

If no at 360 or upon completion of 365, the system then determines ifcompensation is needed at 370. If yes at 370, the system checks, at 373,if the commanded velocity or jerk input has changed, and, if yes, thesystem will jump to setup a new compensation curve at 390. If not, thesystem evaluates the current compensation curves for acceleration,velocity, position and the like at 375 and then returns to 355 toreceive the next inputs. If no at 370 (checking if the system is incompensation), then at 380, the system processes acceleration, velocityand position input signals.

At 385, the system then checks if the position is lagging behind theinput (which could mean either ahead or behind in setpoint depending onwhether the master is decelerating or accelerating (which is furtherdependent on the commanded velocity and acceleration). If yes, thesystem sets up and starts a new compensation curve at 390. If no at 385,the system than checks if the commanded velocity or jerk have changed at395. If yes, the system moves to set up and start a compensation curveat 390, otherwise, the system returns to receive inputs at 355. In anycase where the method proceeds to 390 to setup and start thecompensation curve, the method then returns to receive inputs at 355.

In the above method, a compensation curve can be set up based on jerk,acceleration, velocity and position changes via curves such as thoseshown in FIG. 5 . For example, to achieve a velocity change, the curvecould end at the halfway point shown in FIG. 5 . Further details areprovided below.

As noted herein, there are additional complexities when a moving elementon a conveyor operates in synchronization with an automation station orsimilar combinations of different equipment that need to havecoordinated activity. In the conveyor example given above, a movingelement can move between synchronous areas or zones where there iscoordinated movement and asynchronous areas or zones where the movingelement can be controlled by the conveyor system separately. Forsynchronous areas that begin with non-zero moving element velocities, an“On-the-Fly” merge needs to be performed when transitioning from anasynchronous to synchronous area to align the moving element to themaster signal of the synchronous area. In these cases, the movingelement needs to be at the correct location, with the correct velocityat the correct master value in order to synchronize with the mastersignal.

One of the issues that was found in this synchronization was that notallowing for jerk-controlled motion could result in missed merges,over-currents, excessive power draw, aggressive moving element behaviorand other issues. The following description relates to a method formanaging an automation system and, more specifically, a method forjerk-controlled compensation intended to merge (transition) a movingelement into a sync area in various scenarios while avoiding at leastsome of the issues identified with conventional systems. Further, themethod/algorithm is intended to be executed in an efficient manner on anembedded controller while ensuring a smooth transition betweenasynchronous and synchronous areas without complex configuration effortrequired from an end user while reducing or minimizing the size of thetransition (merge) area.

FIG. 4 illustrates another method 400 for managing automation systemsaccording to an embodiment. In particular, the method 400 relates tomanaging movement of a moving element on a conveyor between an area ofasynchronous motion and an area, of synchronous motion. In thisparticular example, a moving element is controlled to work with, forexample, an automation station in a synchronized manner.

Generally, the method 400 includes: deriving a plurality of jerk-basedcompensation curves (for example, 4 curves) and combining these over theduration and length of a merging area. The compensation curves can bederived with respect to the moving element's and automation station'simmediate motion characteristics to provide for a smooth transition. Thecompensation curves are initially derived with respect to time. Thecombined curve is executed with respect to a master signal (for example,the automation station's signal) in order to cover the case of themaster signal switching its velocity during the merge. The method 400and the use of compensation curves are intended to allow for cases wherethe moving element is late or early including those where the movingelement needs to stop to properly align the timing of the merge.

As shown in FIG. 4 , the method 400 begins when a moving element(sometimes referred to as a “pallet”) enters the merge zone at 405. Thesystem then determines the time remaining to enter the sync area/zone at410. The time remaining can be determined, for example, by assuming themaster begins to accelerate to maximum velocity immediately, calculatingthe lowest possible amount of time for the current merge. The systemthen determines if the pallet is accelerating at 415. If yes, then thesystem determines, at 420, an abort for the current acceleration basedon a resulting final velocity/position after the abort. If not at 415 orafter 420, the system determines the next possible index for alignmentat 425.

At 430, the system determines if the pallet should stop. The calculationto determine if the pallet should stop can be based on various factorssuch as: a calculation of the extremes of the velocity compensationprofile, noting if the velocity either dips below the 0 point, above themax velocity or finally if the change in velocity is larger than the oneattainable based on acceleration, jerk parameters, and the like. If yes,at 435, the system will stop the pallet at the calculated minimumstopping position and determine the next possible index and when tostart moving at 440.

If no at 430 or after 440, the system then determines the velocitycompensation profile needed at 445. The system also determines theposition compensation profile needed at 450. The compensation curves aredetermined in a way that is intended to ensure no moving elementcollisions can occur with the moving element in front. The compensationfunctions by aligning the moving element to the backwards propagatedentry-constant velocity curve. The moving element is aligned to both thevelocity and the position simultaneously over the course of the merge.By aligning the moving element with the entry curve, the system/methodis intended to ensure no collisions with moving elements in front of itthat could be following this entry curve. By examining FIGS. 6 and 7 ,which illustrate compensation curves, one can see that the Pallet MergePosition curve never crosses the Straight Line Entry Move Position Curve(the top left plots in each figure). At 455, the method/system logs basemovement characteristics of the master signal that were used tocalculate the compensation profiles for velocity and position. Themethod/system then later uses these characteristics to execute theprofile with respect to master degrees, instead of time.

At 460, the system calculates additive jerk to be applied to the palletbased on compensation profiles. The system then determines if the masterposition change is different from the base logged at 465. If yes, thesystem interpolates jerk based on base movement characteristics at 470.If no or following 470, the system applies the jerk value to the palletat 475. The system then checks if the merge is complete at 480. If not,the method returns to calculate additive jerk at 460. If yes, the methodends at 485.

FIG. 5 illustrates a sample compensation curve in relation to position,velocity, acceleration and jerk. The compensation curves can be used asnoted above and during a merge operation from asynchronous tosynchronous areas/zones. Based on the plots in FIG. 5 , the followingequations can be determined:

T=4*t _(a)+2*t _(c)  (1)

a _(max) =J _(max) *t _(a)  (2)

Δv=(2*t _(a) *a _(max))/2+t _(c) *a _(max)=(t _(a) +t _(c))*a_(max)  (3)

Δd=(4*t _(a)+2*t _(c))*v _(max)/2=(2*t _(a) +t _(c))*v _(max)  (4)

In these equations, the knowns are T, a_(max), and Δd and the unknownsare t_(a), t_(c), and J_(max). From (1) we can derive:

t _(a) =T−2*t _(c)/4  (5)

From (3) and (4), we can derive:

Δd=(2*t _(a) +t _(c))*(t _(a) +t _(c))*a _(max)=(2*t _(a) ²+3*t _(a) *t_(c) +t _(c) ²)*a _(max)  (6)

From (6) and (2), we can derive:

J _(max) =a _(max) /t _(a) =Δd/(2*t _(a) ³+3*t _(a) ² *t _(c) +t _(a) *t_(c) ²)  (7)

Plugging (5) into (6), simplifying, and solving for t_(c) gives us:

t _(c)=4*Δd/(a _(max) *T)−T/2  (8)

This equation (8) has all knowns, so we can solve for t_(c) and plugback into (5) to get t_(a), which we can then plug back into (7) to getJ_(max).

These equations can be used to determine position compensation curveswith respect to jerk and time. It is noted that upon completion of thecurves above, the only overall change can be a change in position, andby organizing the curves as shown in FIG. 5 , it is possible to simplifytheir calculation, which can be beneficial to run this method/system onan embedded controller (typically having limited memory and/orprocessing power). This solution helps to overcome previous issues ofusing jerk-controlled motion, such as the solving and processing ofcubic polynomials. Using jerk controlled motion profiling can help toreduce power draw spikes and reduce wear on moving element components.Overall, the methodology stated above allows the use of jerk in, forexample, a “maximum jerk allowed” configuration, without compromisingperformance and risking cycle-time violations or the like. As seen inFIG. 5 , velocity and acceleration compensations look the same and canbe cut off at the half-way and quarter way points, respectively. Thecurves are generally calculated in order: acceleration, velocity andlastly position, using the current time left to merge at the time ofcalculation. This is done since the acceleration curve will produce achange in both velocity and position, and the velocity curve willproduce a change in position that need to be accounted for when figuringout the curves needed to align the moving element to the entry motionprofile. The time left to merge can be based on the current(instantaneous) velocity and position of the master. It is noted thatthese parameters/compensation curves generally function best in an“ideal case” where the master signal does not change velocities. FIG. 6illustrates a comparison between a straight-line entry and a palletmerge using an embodiment of the system and method herein. FIG. 6illustrates an “ideal case” in showing the additive overall compensationprofile executed in the case where a master signal does not changevelocity in the merge (as noted by the straight-line entry velocity bluecurve being constant). The acceleration curve is executed at the startof the merge, and after it is complete the velocity curve is executed.The position compensation curve is executed throughout the entire mergesince it does not affect overall velocity or acceleration change. FIG.14 shows the additive jerk profiles separately (calculated for theacceleration, velocity and position compensation curves). The rest ofthe curves can be integrated from the additive jerk curve.

To address a more general case, for example, involving a velocity changein the merge, the ‘ideal’ calculated compensation profile can beexecuted with respect to degrees traveled by the master signal insteadof with respect to time. This allows the method/system to ‘stay in sync’with the master signal, accounting for slow downs, speed ups, or evenstops of the master signal mid compensation profile-execution. Theinterpolated execution with respect to master signal degrees instead oftime is done by advancing the ideal compensation profile and theninterpolating between 2 sets of discrete points (for example,discretized by an 800 us controller cycle) with respect to the ratio ofhow much the master has advanced in the current scan versus how much itwould have advanced based on the initial characteristics logged earlier.FIG. 7 shows the same type of ‘ideal’ case shown in FIG. 6 but executedwith respect to a velocity changing (decelerating) master signal. Notethat the straight-line entry velocity does not stay the same throughoutthe merge and gradually changes. In FIG. 7 , it can be seen that, basedon the time x-axis, that the merge completes later on (crosses the 0position y-axis). In some cases, in working with time-basedcompensation, an additive jerk can be added to the entire compensationprofile any time the master experiences acceleration/deceleration. Theadditive jerk can be, for example, scaled based on the maximum mergevelocity to maximum master velocity relationship.

By deriving the merging compensation curves with respect to timeremaining to complete a merge at the moment of derivation, the act ofmerging can be de-coupled as being a static curve with respect to themaster position. Because of this, it is possible to use theimplementation to enable variable merging, where it is possible toassign an arbitrary degree value at which point the pallet should besynchronized moving at a designated velocity at the start of thesynchronous area. Coupled with the external master implementationexplained above, the variable merging technique allows forsynchronization with other types of conveyors, such as belt conveyors,which generally have variable pitched and constant velocity. Asillustrated in FIG. 15 , a first conveyor is provided with pallets and asecond conveyor is provided with workpieces with the goal ofsynchronizing the workpieces with the pallets so that, for example,workpieces can be placed on a pallet. In this case, the first conveyoris a linear motor conveyor with independently controlled pallets and thesecond conveyor is a belt conveyor with variable pitch and approximatelyconstant speed, however, it will be understood that the first and secondconveyors may also be the same type of conveyor. A synchronizationoperation includes receiving an input signal (trigger signal) from a PLCas a workpiece on the second conveyor is entering a merging, or staging,area prior to a synchronous area. The trigger signal is used todetermine the master signal degrees or time prior to the workpiecereaching the synchronous area. A controller can then synchronize ormerge an incoming pallet to align with the workpiece at the start of thesynchronous area by setting a custom merge time and degree value. Sincethe movement profile of the pallet is executed with respect to mastersignal degrees, any slow down in the second conveyor's master signalwill also translate to the first conveyor/pallet, ensuring thatsynchronization is achieved upon entering the synchronous area, aftercrossing the merging area. The pallet and workpiece can then travelsynchronously at constant velocity, while maintaining relative position.

As illustrated in FIG. 15 , the master signal approach with compensationcan also be used to synchronize conveyor to conveyor for variousoperations where two conveyors may need to be synchronized. In somecases, if the conveyors are of the same type and same manufacturer, orthe like, any compensation required may not be as significant and couldbe set accordingly. Similarly, the jerk compensation approach can beused in various applications to synchronize various elements of anautomation system. Although the master signal approach and the jerkcompensation approach have been described together herein, one of skillin the art will understand that each approach may be used separately aswell and that portions of each approach may be used with the other asappropriate for particular applications.

In the preceding description, for purposes of explanation, numerousdetails are set forth in order to provide a thorough understanding ofthe embodiments herein. However, it will be apparent to one skilled inthe art that these specific details may not be required. In otherinstances, well-known structures or circuits may be shown in blockdiagram form in order not to obscure the overall system or method. Forexample, specific details are not provided as to whether the embodimentsdescribed herein are implemented as a software routine, hardwarecircuit, firmware, or a combination thereof.

Embodiments can be represented as a software product stored in amachine-readable medium (also referred to as a computer-readable medium,a processor-readable medium, or a computer usable medium having acomputer-readable program code embodied therein). The machine-readablemedium can be any suitable tangible medium, including magnetic, optical,or electrical storage medium including a diskette, compact disk readonly memory (CD-ROM), memory device (volatile or non-volatile), orsimilar storage mechanism. The machine-readable medium can containvarious sets of instructions, code sequences, configuration information,or other data, which, when executed, cause a processor to perform stepsin a method according to an embodiment. Those of ordinary skill in theart will appreciate that other instructions and operations necessary toimplement the described embodiments can also be stored on themachine-readable medium. Software running from the machine-readablemedium can interface with circuitry to perform the described tasks.

The above-described embodiments are intended to be examples only.Elements of one embodiment may be used with other embodiments and notall elements may be required in each embodiment. Alterations,modifications and variations can be effected to the particularembodiments by those of skill in the art without departing from thescope of the invention, which is defined solely by the claims appendedhereto.

What is claimed is:
 1. A method for managing an automation systeminvolving asynchronous and synchronous zones, the method comprising:determining when a moving element enters a merge zone between anasynchronous zone and a synchronous zone; calculating additive jerk tobe applied to the moving element, wherein the additive jerk is based onpredetermined compensation profiles; determining if the master positionchange is different than a base logged; if so, interpolating additivejerk based on movement characteristics of the moving element; in eitherevent, applying the additive jerk to the moving element; determining ifthe merge is completed, if yes, ending the merge and continue withsynchronous operation but, if no, returning to calculating the additivejerk and repeat.
 2. A method according to claim 1, wherein thepredetermined compensation profiles are determined in advance to reducecomputation time and complexity.
 3. A method according to claim 1,wherein the predetermined compensation profiles comprise a velocitycompensation profile and a position compensation profile.
 4. A methodaccording to claim 1, wherein calculating additive jerk based onpredetermined compensation profiles comprises determining the movementcharacteristics of the moving element based on the compensationprofiles.
 5. A method according to claim 1, further comprisingdetermining if the moving element needs to stop prior to or within themerge zone to allow synchronization.
 6. A method according to claim 5,further comprising calculating a minimum stop position based on maximumentry velocity.
 7. A method according to claim 1, further comprising:determining worst case time remaining before entering the synchronouszone; determining if the moving element needs to stop; if so, stop themoving element at a minimum stopping position and determine when tostart moving and next possible index; in either case, determiningvelocity compensation and position compensation profiles to matchvelocity and position; and determining the movement characteristicsbased on the compensation profiles.
 8. A system for managing anautomation system involving asynchronous and synchronous zones, thesystem comprising: a first controller for controlling a firstsynchronous element; a second controller for controlling at least asecond synchronous element; a configuration module for configuring theautomation system; a memory storing instructions that, when executed bythe second controller, cause the second controller to: determine when amoving element enters a merge zone between an asynchronous zone and asynchronous zone; calculate additive jerk to be applied to the movingelement, wherein the additive jerk is based on predeterminedcompensation profiles; determine if the master position change isdifferent than a base logged; if so, interpolate additive jerk based onmovement characteristics of the moving element; in either event, applythe additive jerk to the moving element; determine if the merge iscompleted, if yes, end the merge and continue with synchronous operationbut, if no, return to calculating the additive jerk and repeat.
 9. Asystem according to claim 8, wherein the predetermined compensationprofiles are determined in advance to reduce computation time andcomplexity.
 10. A system according to claim 8, wherein the predeterminedcompensation profiles comprise a velocity compensation profile and aposition compensation profile.
 11. A system according to claim 8,wherein calculating additive jerk based on predetermined compensationprofiles comprises determining the movement characteristics of themoving element based on the compensation profiles.
 12. A systemaccording to claim 8, further comprising determining if the movingelement needs to stop prior to or within the merge zone to allowsynchronization.
 13. A system according to claim 12, wherein theinstructions further comprise causing the second controller to calculatea minimum stop position based on maximum entry velocity.
 14. A systemaccording to claim 8, wherein the instructions further comprise causingthe second controller to: determine a worst case time remaining beforeentering the synchronous zone; determine if the moving element needs tostop; if so, stop the moving element at a minimum stopping position anddetermine when to start moving and next possible index; in either case,determine velocity compensation and position compensation profile tomatch velocity and position; and determine the movement characteristicsbased on the compensation profiles.